Gyro-compass.



J PERRY & S. G. BROWN.

GYRO COMPASS.

APPLICAHONIHLED' AUG. 1, 191 7.

1,291,695. Patented Jan. 14, 1,919.v

. 4 SHEETS--SHEEI I.

J J T; i a a v I Q 0 n l all 0 I F e /Z 1f j 10f Inventor}:

M wzg J. PERRY & S. G. BROWN.

GYHO COMPASS.

APPLICATION HLED AUG-7.191].

1,291,695. Patented Jan. 14-, 1919.

' 4 SHEETS-SHEET 2- J. PERRY & S. G. BROWN.

GYRO COMPASS.

APPLICATION FILED AUG. 7. I917.

' 1,291,695 Patented Jan. 14,1919.

4 SHEETS-SHEET 3 I Immtw J. PERRY & S. G. BROWN GYRO COMPASS.

APPLICATION FILED AUG-7.191?

Patented 112111.14, 1919.

4 SHEETS-SHEEI 4 JOHN PERRY, or KENSINGTON,

LONDON, AND SIDNEY GEORGE BROWN, OF NORTH .ACTON', ENGLAND.

GYRO-COMPASS.

Specification of Letters Patent. Patentd J an, 14, 1919.

' Application filed August 7, 1917. Serial No. 184,955.

T all whomet may concern.

Be it known that we, JOHN PERRY and SIDNEY GEORGE BROWN, both subjects of the King of Great Britain, residing, respectively, at 25'Stanley Crescent, Kensington, in the county of London, England, and Edward Road, Willesden Lane, North Acton, in the county of Middlesex, England, have invented certain new and useful Improvements in or Relating to Gyro-Gompasses, of which the following is a specification.

This invention relates to the construct on of gyro-compasses especially for. use on ships, and has for its chief object to provide the necessary gravitational control of the gyroscope, which gives the .north seeking property, without subjecting the gyroscope to appreciabledisturbing forces due to rolling, pitching or other short period motions of the ship. The compass may .be of the general type described in the specification of our United States application No. 60,770 in which thefrictionaround the vertical axis of a gyro frame mounted in a pendulous support is substantially eliminated by means of areciprocating movement; the

present invention however is not confined to any special type of compass.

According to this invention the pendulous or gravitational factor which controls the gyroscope acts through a relay or intermediate source of power. The pendulous faetormay therefore be made very small compared to the mass of the gyroscope, and the gyro-casing, including the gyro wheel and any parts moving with the casing, may be mounted substantially in neutral equilibrium so that rolling or other periodic or irregular movements of the ship exert no direct torque upon the gyro-casing.

The rotation of the gyro wheel in its cas-. ing causes rotatory movement of the air in the casing and an outwardly directed pressure of air, due to centrifugal force; we

may utilize this air as the intermediate source of power by directing, for example, the air fromv a nozzle into two channels. leading to a weight displacing device by which weight may be shifted from one side to the other of a -t-ransverse lever preferably at about the level of the gyro axis. The weight displacing device preferred is in the form of a pair of communicatingbottles or vessels at opposite sides of the axis of the gyro-casing and containing oil or other liquid, the gravitationa'l factor or pendulum controlling the air. jet so as to vary the pressure in the channels and cause flow of oil from .one bottle to the other according to the direction in' which the righting torque is to be applied. -It'will be seen that as the controlling weight is at the end of a substantially horizontal lever arm it is in the most eflicient position for exercising its controlling force, in contrast to the direct control of a pendulum which for small displacements is at its position ofminimum efficiency. A characteristic-of great importance is due to the fact that the weight displacement is out of phase with the movement of the gravity control orpendulum, since the maximum differential air pressure and consequently maximum movementof the liquid occur at the end of. the pendulum swing when the pendulum is moving at its minimum speed,

nated, as has been found experimentally.

To exercise a strong damping effect on any oscillations of the gyrocas ing which may be set up,we may employ a second set of air controlled oil bottles or vessels working in opposition to the main bottles but with a more contracted passage'so as to cause slower flow of oil and consequently a large time lag. The difference in phase producesthe desired damping action.

In order that the said invention may be more clearly understood and readily carried into effect, we .will describe the same more fully with reference to the accompanying drawings, in which':

Figure 1 is an elevation of the gyro-compass embodying our invention, with the gimbal rings in section.

Fig. 2 is a view at right angles to Fig. 1, partly in section on the line a;-:v Fig. 1.

equilibrium the quadrant-a1 error is elimiw Fig. 3 is a sectional plan on the line e 1 Figs. 7 and 8 show a modification of the in Figs. 1 to 6, A is the gyro-casinglwithin which the wheel rotates around a normally horizontal axis. B is the orienting frame or ring carrying the card 6, within which frame the casing A is free to turn around ,the horizontal axis a at right angles to the gyro axis. C is an outer pendulous frame tarrying the.frame B which, can turn around the vertical axis 6' and 1s reciprocated along that axis so as to reduce the frlction to a minimum-in accordance with our specifica 'tion- No. 60770 already referred to. bearing and means for producing reciprocation are inclosed inthe box 0 at the bottom of the frame C, which is mounted in the usual gimbal rings D. ;E is an airnozzle on the casing A, through which a small jet of airescapes'at a pressure depending upon the action of the rotating gyro-wheel. The nozzle projects through'an opening in the frameB. F is-a-pendulumarm carrying a small shutter or air director f which partly -covers the nozzle E and directs the air to one side or the other according to the angularposition of the pendulum. G, G are two small communicating oil bottles mounted on the casing A receiving the pendulum floats f whichrest on the oil in the bottles G so that the pendulum F is controlled by the difi'erential oil level. H, H are the main'oil bottleswhich exercise the righting torque around the axis m of the casing A. J, J are the second pair of bottles acting around the axis ato produce damping of the oscillations. K is a small air chamber or box pro vided by; the blade-or partition 70, .(see the detail. plan, Fig.6) ,into two compartments into, which the air from the nozzle E is directed in a variable mannen Each compartment is connected by the small pipe is to an air pipe'le connecting the upper end of one bottle H to the bottle J at the opposite side of the axis a, thebottles being cross con'-' nected in pairs as shown in Fig. 3.: The bottom connections for the oil are through the pipes 71. and j respectively for the pair of bottles H and J, so that oil can flow in one direction between thetwo bottles H accord ing to the relative air pressures on the two surfaces and in the opposite direction between the two bottles J, the passage in the latter case being considerably more re. stricted to give a substantial lagin attaining The lated to any required degree.

equilibrium. The rate of flow may be ad dition to be attained adjustable weights L are mounted onarms Z extending from the lower side of the frame B in the vertical plane through the gyro axis, the weights beset so that thetotal amounts of inertia, including that of the. casing A, are balanced v andthere is no tendency for the gyro mount- ,ing to set itself in any special relationship to the plane of roll or pitch of the ship.

Owing to theneutral equilibrium of the casing A gravitation exerts no direct control over its position but any tilt relatively to the vertical (which continuously changes its position in" space as'th'e earth rotates) acts upon the'pendulum F through the oil in the pendulum bottles G, the oil flowing fromone bottle to the other according to the direction of tilt of the casing A. As shown more especially in the detail views Figs. 4 and-5 the bottles G are carried on a, base '9 mounted adjustably on a bracket gwhich is fittedto. the casing A, the adjustment of the bottles and attached parts for balancing being effetted by the screw 9 acting against the spring g The oil passage 9 between the bottles is restricted bythe adjustable needle valve 9 so that the rate of flow can be regu- The pendulum arm F is mounted on the knife edge bearing f on posts 9 on the base (7 and the floats f ar'e at the ends of the curved cross arm 1 which passes through the covers of the bottles G. Any change in relative level of the oil in the bottlesG due to tilting of the casing A causes the arm F to turn relatively to the casing and consequently moves the air director or shutter facross the nozzle E (see the detail views Figs. 5 and 6). with theresult that the air is deflected-unequally into the two compartments of the box K causing unequal pressure in the opposite pipes la. The director f may be a simple fcentrally placed bar as shown or maybe in the form of a small plate with air hole which directs the air into the chamber K.

The pipes k and cross pipes 70 are so connected to the main bottles H that the dif position. As long as the tilt exists the oil r horizontal lever arm so that a small addibottles H are out of balance and the torque continues, the strength of the torque depend- 1' ing upon the difierential'pressure of air, that i H is now almost equalized.

is upon the amount of tilt, and upon the scribed, a more restricted oil channel between them. Since these bottles J act against the bottles H the righting torque is reduced by an amount depending on the oil displacement in the bottles "J but such displacement has a considerable time lag and -for short period disturbances the righting torque is not substantially reduced, while the difference in phase between the action of the two pairs of bottles rapidly damps out any oscillations of the casing A which may have. been set up and consequently damps the associated oscillations of the com pass around the vertical axis 1).

Asalready pointed out the controlling weight acts-at the end of a substantially tion of weight to one side or the other exerts an appreciable righting torque which torque is variable and out of phase with the pendulum;

While short period, movements such as rolling and pitching of the ship have no di- Y rect disturbing effect on the gyro-system owing to the fact that it is mounted in neutral equilibrium such movements cause acceleration pressures on the oil. in the various bottles whlch would, if uncompensated, cause so 1e disturbances in the balance.

As however the relation between the torque applying and the pendulum bottles is under control by the adjustment of the oil passage between the bottles G, the small effects of short period movements on the pendulum may be made to cause such differential air pressures in the bottles H and J as will compensate for the acceleration pressure on the oil in these bottles so that no appreciable disturbance of the compass reading is caused by such short'period movements.

The pendulum device above described is one specially designed to give a normal condition of neutral equilibrium which remains substantially unaffected by short period movements of the compass while responsive to the slow changes in the vertical dueto rotation of the earth, but other long period pendulum arrangements may be employed; for example, a small auxiliary gyroscope may be attached to a pendulum or equivalent gravity-control device, such gyroscope &

lengthening the natural period, as is well known, or the pendulum may be connected to a damping device which prevents.appre-.

ciable short period movements but allows the pendulum to respond to long period forces.

The modification shown in Figs. 7 and 8 employs a pendulum controlled by an auxiliary gyroscope.

In this construction a' pendulum F is mounted on knife edge hearings on the end,

of a bracket arm n belonging toa bracket N which, as in the case of the bracket 9' carrying the bottles G, extends from one face of the gyro-casing past the edge of the frame or ring B.

, A downwardly extending bracket arurn. carries a small dash pot M containing a viscous liquid into which the lower end of the pendulum F extends. The upper end of the pendulum is made in the form of a rin f inclosing'a small auxiliary gyro-wheel 6 mounted in a frame 0 which is carried on vertical pivot points 0 in the ring f. The axis of the gyro'wheel O is level and parallel with the axis of the main' gyro and the rotation is in the same direction.

Any force exerted on the pendulum F tending to cause angular displacement is resisted by the gyro-wheel O which is free to precess around its vertical axis. A small centralizing spring'o connected to the frame 0 acts to return the gyro-wheel to its normal central position parallel to the plane of the main gyro-wheel or gyro-casing A.

The pendulum F is stabilized by the small auxiliary gyroscope and is almost unaffected byshort period disturbances, but responds to the slow change in the vertical due to the rotation of the earth. The air control may illustrates a damped pendulum which may take the place of either of the pendulum dei/ices already described and also a different method of applying the righting torque to the gyro casing. Only one side of the casing is shown but it is to be understood that the I a righting torque by the differential action of two air nozzles E, one on each side of the casing and oppositely directed, so as to discharge the air and cause a reactive pressure against the-external air acting around the horizontal axis' (1. of the casing A. In this modification a dash pot M containing a very viscous fluid, such as beeswax, is

mounted on an arm m turning about an axis on and supported in brackets m mounted on the casing A, the dashpot receiving at one side a fixed blade m secured on the casing and at the other the lowerblade end of a pendulum F mounted on an axle 7? that carries the two arms 7 and the air director f which lies in front of the nozzle E, made as shown in Fig. 8, in the form of a long narrow slit. d

It will be seen that any tilt of the casing causes a retarded relative movement of the pendulum F throughthe dashpot M, which displaces the air director f over the nozzle,

@increasing or reducing the effective air aperture according to the direction of movement. At the other side of the casing A thesirnllar devicecauses an opposite displacement so that there is a ,difierenti-al. air discharge through the two nozzles E and consequently 1 the nozzle instead of being utilized to pro a reaction against the external air which generates a righting torque around the axis a of the casing A. The air director prefera-bly half covers the nozzle E in normal .position. Asmall Weak restoring spring 7 tends to return the pendulum F fto normal position relatively to thecasing Various other methods of utilizing a relay action in the control of the gyroscope can be employed. For example, the 'air blast from duce pressure may act through an elect ic circuit, the nozzle being placed between. two

heated wires which it cools differentially so as to control an electric current to a motor adapted to'exert a'righting torque on the the axis of the gyro-casing-.A,' a permanent magnet 19 providing the field for the motor. The motor'current varies in direction and strength according to the relative cooling of the Wires f no current flowing to the motor when the wires f are of equal temperature while any displacement'due to tilting of the casing and consequent movementrelative to thependulum F moves one or other of the wires into the air blast and causes differential cooling of the wires and a righting torque. around the axis of the casingA which dependson the strength of the current through the motor.

Inthe modification shown in Fig. 12- the air blast device is controlled by the pendulous mounting of the gyroscope itself in the frame C (Figs. 1 and 2) the vertical axis of the orienting frame or ring B coinciding with the axis 7) of the frame C. The air f nozzle E and'air box K are carried by the gyro-casing A as in the constructions illustrated inFigs. 1 to 8, the nozzle projecting 'movements of the casing A and frame B.

tain its axis of rotation vice.

through an aperture in the frame B while a small arm F f is fixed to the frame B below the knife edge a"'of the casing A andprojects in front of the nozzle E. Any tilting of the casing-A relativelyto' the frame'B causes differential action of the air blast on is thus avoided; v

Instead of an air deflecting arm such as F 4 a small conical movable jet F secured on theframe B may be provided, as shown in 80.- Fig. 13, the jet being placed just in front of. v the airnozzle E and leading the air through a reduced aperture which moves relatively to the air box K according to the relative Y What we claim and desire to secure by- Letters Patent of the United States is 1. In; a gyro compass, a gyroscope, mounted so that its axis may be oriented in the NS direction, a gravity controlled device and an independent source of'power controlled by the said gravity device and adapted to act upon the gyroscope to main-.

in the "NS direction. v V. i an 2. In a gyro compass, a gyroscope includ- 'inga gyrocasing mounted in substantially neutral equilibrium around" its horizontal axis, so that the axis of rotationof the gy- L roscope maybe oriented i'nthe N S*di- 1 rection, a gravity controlled device and an independent source of power controlled by the said gravity deviceand adapted to act upon-the gyroscope around its horizontal axis of suspension so as to maintain its axis of rotation in the N-S direction.

3. In a gyro compass,'a gyroscope includ ing a gyro-casing mountedto turnabout a horizontal axis, a. weightdisplacing device by which mass may be moved across the axis of the gyro-casing, a gravity .controlled device and an independent source of power controlled by the gravity device to eflect the operationnof the weight displacingdev 4. A gyrocompass as claimed in claim 1, comprising a gyro casing filled with air and'having a directive air outlet under the control of the gravity device. V

5. A gyrocompass as claimed in claim 4 provided with a diderenti'al air director for the said air-outlet, by which airdirector the gravity device exercises its control.

6. In a gyro-compass, a gyroscope ineluding a gyro-casing mounted to turn about 12:3 a horlzontal axis, a pairof interconnected liquid vessels mounted on the casing at op- 'posite sides of its said' axis, a gravity de-' vice and-a source of power controlled by the said gravity device to displace liquid from one vessel to the other, for the purpose specified.

6 a ro-casin filled with air. and orojvided with an air o'utletfan' .air director under:

gravity control and air channels into which theair i's differentially directed and through which pressure is applied to the liquid in the aforesaid vessels, for the. purpose specified. 8. In a gyro-compass as claimed n elamil 6, a second pair of. 1nterconnected llqllld.

vessels having a more restricted com-municatl ng' passage and -.means for displacing liquid in the opposite direction to the displacement in the main vessels but at a slower rate, for the purpose specified.

9. In a gyro-compass, a gyroscope comprising a gyro-casing mounted to turn around a horizontal axis and a frame carrying the gyro-casing, a small pendulum de-j -v1c e comprising .a pair of communicating vessels partly filled with liquid and-mounted at each side of the casing axis and a pivoted lever earryingia pairfof floats supported by the liquid in the said vessels,-and a source of power controlledhy the said pendulum device and adapted to exert torque around the axis of the said gyro-casing, for the purpose specified. p

10. In a gyrocompass, a gyrocasing filled with air and provided with an airoutlet a pair of interconnected liquid vessels mounted on the casingon opposite '.sides 0f its axis, a pair of ainehannels connected to the said vessels, a gravity'c'ontrolled device and an air director deflecting the air differentially-"into the said channels under the control of the said gravity device, for the purpose specified.

JOHN PERRY; SIDNEY GEORGE BROWN. 

